Depression of the Megakaryocyte-Platelet System in Rats by Transfusion of Platelets

Abstract

Effects of hypertransfusion of platelets on the megakaryocyte-platelet system were investigated, especially in relation to mechanisms regulating platelet production and homeostasis. Rats were transfused with large numbers of platelets, and the number of peripheral platelets, the number of megakaryocytes in the marrow, and the rate of platelet production were assessed. The platelet count gradually declined, fell below normal, and then returned to normal. Megakaryocytes were significantly reduced 3 and 4 days after transfusion. Labeling of platelets 48 hr. after injection of Na2S35O4 was also reduced in rats hyper-transfused with platelets. The results support the hypothesis that abnormally high numbers of platelets in the circulation inhibit the production of new platelets, possibly by inhibiting proliferation of a megakaryocyte precursor.